(a) Field of the Invention
This invention relates to polymers with improved performance characteristics. In particular the invention relates to compositions comprising a poly(aryl ether ketone) having intimately dispersed therein from about 0.1 to 5% sulfur, by weight, based on the weight of poly(aryl ether ketone).
(b) Background Information
Poly(aryl ether ketones) are known in the art and are tough, rigid, high-performance thermoplastics which have excellent mechanical and electrical properties. Articles formed from them maintain their properties over a wide temperature range and can be used continuously at high temperatures.
In U.S. Pat. No. 3,993,628 to Jarrett et al it is disclosed that mixtures of an aromatic copolyetherketone/sulfone, containing 3 to 9 ketones links per sulfone linkage, with sulfur or a sulfur compound exhibit an increase in molecular weight and the polymer cross-linked upon heating. It is reported that the corresponding polyetherketones, i.e. without any sulfone links, do not exhibit an increase in molecular weight upon heating. It is further reported that when a polyetherketone was and 1% elemental sulfur were powder blended and then compression molded at 400.degree. C. for 15 minutes, the polyetherketone was found to have decomposed without forming of a coherent film.
We have now discovered that if sulfur or a sulfur compound as hereinafter defined is uniformly dispersed in a polyarylether ketone the properties of the polymer are significantly and surprisingly improved. In particular we have found that a poly(aryl ether ketone) having uniformly dispersed therein sulfur or a sulfur compound exhibit improved tensile modulus, creep resistance and in particular their adhesive properties, especially at high temperatures.